Automatic case stacker

ABSTRACT

A case or carton-stacking machine is provided where one article after another is carried at properly-spaced intervals by an endless conveyor onto a vertically-movable plate that is raised and lowered by a ram or air cylinder and piston. When a carton is carried to a selected position in the apparatus, it triggers the operation of a ram that raises the article above opposed supporting dogs which then move into position below the article to keep it elevated while the ram returns to its lower level. When the next case or carton then strikes the trigger, the ram operates to raise the second one up under the first so that two articles are then supported, one above the other, on the dogs. This cycle repeats until the stack reaches a predetermined height when the dogs are held out of stack-supporting position and the stack is lowered with the ram until it rests on the endless conveyor and is removed. Provision is also made for removing the stack while it is supported on the dogs when the stack is to be removed at a level above the conveyor level. For stacking cartons with cover flaps, a coverflap-closing unit is attached to the stacker.

United States Patent [1 1 Alduk [4 1 Feb. 18, 1975 1 AUTOMATIC CASESTACKER Frank P. Alduk, 1 16 Guadalcanal Rd., New Castle, Pa. 16105 [76]Inventor:

[52] US. Cl. 214/6 BA [51] Int. Cl. t B65g 37/30 [58] Field of Search214/6 BA, 6 P

[56] References Cited UNITED STATES PATENTS 2,857,040 10/1958 Campbell214/6 BA X 2,904,941 9/1959 Midnight 214/6 BA X 3,039,624 6/1962Campbell 214/6 BA 3,053,402 9/1962 Russell et a1. 214/6 BA 3,057,48610/1962 Moulthrop et al. 214/6 BA 3,126,104 3/1964 Haselton et al. 214/6BA 3,305,104 2/1967 Hogan et al. 214/6 BA 3,519,144 7/1970 Calistrat214/6 BA 3,570,209 3/1971 Salwasser 214/6 BA 3,643,817 2/1972 Rose .i214/6 BA Primary ExaminerRobert J, Spar Assistant Examiner-Leslie .I.Paperner Attorney, Agent, or FirmParmelee, Miller, Welsh & Kratz [5 7]ABSTRACT A case or carton-stacking machine is provided where one articleafter another is carried at properly-spaced intervals by an endlessconveyor onto a verticallymovable plate that is raised and lowered by aram or air cylinder and piston. When a carton is carried to a selectedposition in the apparatus, it triggers the operation of a ram thatraises the article above opposed supporting dogs which then move intoposition below the article to keep it elevated while the ram returns toits lower level. When the next case or carton then strikes the trigger,the ram operates to raise the second one up under the first so that twoarticles are then supported, one above the other, on the dogs. Thiscycle repeats until the stack reaches a predetermined height when thedogs are held out of stack-supporting position and the stack is loweredwith the ram until it rests on the endless conveyor and is removed.'Provision is also made for removing the stack while it is supported onthe dogs when the stack is to be removed at a level above the conveyorlevel. For stacking cartons with cover flaps, a coverflap-closing unitis attached to the stacker.

17 Claims, 15 Drawing Figures v I PATENTEUFEBI 81975 sum 1 OF 5 m9?" 3PATENTED a SHEET am: 3.866 76 PATENTEB m1 81975 sum a 05 5 PATENTEU FEB]8 75 SHEET t [IF .5

AUTOMATIC CASE ST ACKER This invention is for a machine forautomatically stacking single units, such as cases, cartons, boxes, orpackages of various kinds one on top of another to facilitate handlingor conserve space and thereby avoid much of the manual labor heretoforerequired in stacking the units.

A machine of the general type to which the present invention relates isdisclosed in U.S. Pat. No. 2,857,040 to W. S. Campbell, granted Oct. 21,I958 for an Automatic Case Stacker, but which, so far as I am aware, wasnever developed into a commercial machine, and which appears to beimpractical.

The present invention provides a machine to which units to be stackedare delivered in succession by conveying means where they are admittedone at a time to a mechanism that raises them one under another until astack of the desired height has been formed. When this height isreached, the entire stack is then normally conveyed to the discharge endof the machine. As each unit is raised up, supporting dogs at each sideof the machine move from the path of the ascending unit. As the aircylinder or ram which lifts the unit lowers, these dogs move into aposition where the units are supported on the dogs while the liftingmeans descends to receive the next unit. When the stack has reached theselected height, these dogs may be held out of stacksupporting positionso that the whole stack is lowered onto the conveying means whichthereupon carries the stack to the discharge end of the machine. Howeverthe machine may be selectively modified so the dogs support thecompleted stack and the stack is removed from the machine at a levelhigher than the said conveying means.

Unlike the machine shown in said Campbell patent, the ram alwaysoperates on the same cycle, whether it is raising the first unit of astack or the last. Also unlike said patent the supporting dogs aremechanically moved to and held in an inoperative position when the stackis being lowered to the conveying means. Accidental premature operationof the ram cannot take place. Readily-made adjustments enable onemachine to stack units over a wide range of sizes, so that acustom-built machine is not required for each size of unit. As aboveindicated, the one standard machine can be quickly adapted to deliverthe stack of units at a level higher than the conveyor that brings theindividual units to the stacker, and completed stacks may be selectivelyremoved from either end or either side of the machine.

The machine may also have a carton flap-closing attachment whereby itmay accept for stacking those cartons in which some or all of the coverflaps are only partly closed.

In the drawings showing a preferred embodiment of my invention withcertain modifications to be used where the operation makes it desirableto do so:

FIG. 1 is a side elevation of the machine;

FIG. 2 is an end elevation from the receiving end of the machine withthe restraining device removed and certain parts broken away forillustration with a cast, shown in broken lines, in position for thestarting of a stack of cases;

FIG. 3 is a view similar to FIG. 2 showing the case of FIG. 2 elevated;

FIG. 4 shows a plan view of the bed of the machine, the view being ahorizontal section in the plane of line IVIV of FIG. 2;

FIGS. 5, 6, 7, 8 and 9 represent somewhat schematically the progressiveoperation of the machine in forming a stack of three cases or cartonsfollowing the operations shown in FIGS. 1 and 2;

FIG. '10 is a view similar to FIG. 2 but on a smaller scale showing amodification in which the case is removed from the apparatus at a levelabove the case conveyor and in a direction at right angles to saidconveyor;

FIG. II is a fragmentary detail view of one of the case-supporting dogsand its operating mechanism;

FIG. 12 is a view similar to FIG. 11 of a modified case-supporting dog;

FIG. 13 is a fragmentary side elevation similar to FIG. 1 showing inoutline a conventional carton flapclosing arrangement;

FIG. 14 is a fragmentary side elevation of one side of the stacker ofFIG. 13 with a roller instead of a weight for pressing down on thecompleted stack; and

FIG. 15 is a schematic diagram of one air systemfor operating theapparatus shown in FIGS. 1 to 11.

In the drawings, 2 designates generally a rigid frame formed largely ofhollow square tubing or other struc tural sections 3 substantiallycoextensive with the length of the machine. For purposes of thisdescription, and as here illustrated, the left end of the machine is theentering or receiving end and the right end the discharge or deliveryend. Also, while the machine is here described as a case stacker," theterm case is used in a general sense to include not only cases in whichbottled carbonated or other beverages are contained, but boxes, cartons,packages or other units of various shapes suitable for handling in astack, one on top of another, and cartons which may be closed or havepartially-open flaps that are required to be closed. Also a stack maycomprise two or more articles placed one on top of another, or twoarticles entering the machine side-by-side or end-to-end as a singleunit and stacked pair-on-pair in this relation.

At the left or entering end of the machine there is a transverse shaft 4with spaced sprocket wheels 5 thereon and the opposite end there is asimilar shaft 6 with sprocket wheels 7 thereon. Spaced endless treadtype conveyor chains 8 pass around these sprockets, one near each sideof the horizontal center line of the machine. The shaft 6 ismotor-driven, as indicated by the motor 9 and sprocket chain 10, thischain passing around sprocket wheel 11 on the shaft 6. Being thusdriven, the upper reaches of the conveyor chains are taut and any slackis in the lower or return reaches, as indicated in the drawings. Also,as indicated in the drawings, there is a longitudinally-extendingsupporting rail, not numbered, under the upper reach of each conveyorchain, as is usual with conveyors of this type. The width between thetwo conveyor chains 8 is fixed, but there is a guide bar 12 adjustablysupported above and along the outer side of each conveyor chain 8 foradjustment toward and away from each other to accommodate, center andguide units of different widths. To provide such adjustment, each bar 12has at least two rigid supporting arms 13 fixed thereto and extendinglaterally therefrom toward the outer side of the frame which is nearestthe bar 12. Each arm passes through a support 14 and is slidably fixedin place by a set screw, as indicated at in FIG. 1. The supports 14 neareach end of the machine are fixed on a transverse bar 16 and releasablyheld in place by a set screw 17. Thus bars 12 may be adjusted toward andaway from the center of the machine by loosening set screws 15 andsliding the rigid lateral arms in their respective support members 14.

As best seen in FIGS. 2, 3 and 4 there are continuous support plates 18along the outside edge of the top reach of each conveyor chain 8 and theproximal side rail 3, the surface of which is close to but slightlybelow the level of the conveyors. There are two similar short plates,19a and 19b between the two conveyors at opposite ends of the machine,but which have their confronting ends spaced from each other for thepurpose hereinafter described.

Over the mid-section of the supporting frame 2 there is avertically-elongated structural frame, designated generally as 20,having a pair of upright columns 21 facing toward the left or receivingend of the frame and a pair of similar columns 22 facing toward theright or discharge end. These columns extend up from and are secured tothe horizontal side rails 3 of the machine frame. The tops of thecolumns of each pair, such as the pair of columns 21, are connected bytransverse rigid sections 23 and each pair of columns on the same sideof the machine, comprising one column 21 and one column 22 are connectedat the top by a longitudinallyextending rigid section 24.

The columns 21 and 22 are each provided with a series of closely-spacedholes 25 therethrough extending in the direction of the length of themachine, or what may be termed a fore-and-aft direction, the holes oneach column or post being level with corresponding holes on the otherthree columns or posts.

In the area between the spaced ends of the plates 19a and 19b, which isthe area centered beneath the upright frame just described, there is aninverted U-shaped structure 30 (see FIG. 1) with a flat top or platform31 that is normally level with plates 19a and 19b and with dependinglegs 32. As seen in FIG. 4 the flat top 31 substantially fills thespace, with adequate working clearance, between the spaced ends ofplates 19a and 19b. This structure 30 is fixed to the top of a fluidpressure ram or piston rod 33 of a fluid pressure cylinder and pistonunit 34 so that the plate or top portion 31 can be raised from itsnormal position to a level as shown in FIG. 3 where the piston rod isfully extended.

In the operation of the machine it is expected that the conveyor chainswill carry a case or other unit onto the flat plate 31 at which timepressure air will be admitted to a cylinder 34 to raise the unit upbetween opposed supporting dogs which permit upward movement of saidunit but support it in an elevated position when the support 31 is againlowered. The next unit in turn will be lifted in the same way contactingthe under side of the first one, and the two will be lifted togetheruntil the second unit is also clear above the supporting clogs, when theram will lower and the two units, with the first resting on the second,are then both supported by the dogs. Suppose a stack threecases high isto be formed, the third unit will be raised under the first two and allthree will then lift together, but the first unit, on top, will now beraised to a level where it triggers a release to keep the supportingdogs inactive and the stack of three units will be lowered with the ramto the conveyor which will carry the stack to the discharge end of themachine and the next stack of three will start to form. The mechanismsfor doing this will now be described.

CASE FEEDING AND LIFTING When a case, carton or other package unit to bestacked is delivered from a feed conveyor as indicated or other supplymeans at the left end of the machine onto the receiving end of theconveyor of the stacker, other parts of the machine must be in aposition to take care of it. Therefore the plate 19a has on openingtherethrough through which a stop-member may be projected from anon-obstructing level below the plate 19a to a position above said platemidway between the two conveyor chains where it will restrain a case,carton, or other object from further travel even though the conveyorchains continue to operate. The stop member 40 is mounted on and movedup and down by a doubleacting cylinder and piston unit 41 which ispreferably air-operated. The introduction of air into the bottom of thecylinder raises the stop and admission of air to the top of the cylinderlowers the stop.

To properly space the carton or other unit and prevent one fromcontinuing to move until the previous one has been taken care of, a flagswitch or trigger 42 is positioned along the plate 19a a few inchesbeyond the stop 40, so arranged that when the leading end of the casestrikes it, an air valve will be operated to admit pressure air to thelower end of cylinder 41 to raise the stop 40 to block the travel of asucceeding unit.

A case which has passed the stop 40 is carried by the conveyor onto theplate 31 at the top of the ram cylinder 34. At the end of plate 34 thereis a stop member 43 generally similar to stop 40 which is raised andlowered through an opening in plate 19b by an air cylinder and pistonunit 44, but unlike stop 40, stop 43 is normally raised tocase-obstructing position. Admission of air to the top of the cylinderof the unit 44 lowers the stop and to the bottom of said cylinder thestop 43 is raised to the stop position.

The stop member 43 has an air valve, trigger,- or other self-closingflag switch 45 on that face which confronts the leading end of anadvancing unit, and when a unit has moved sufficiently far over plate 31its forward or leading end will strike this member 45, so that inaddition to the unit being stopped from further travel, pressure airwill be supplied to the lower end of the ram or lifting cylinder 34 tolift the unit. There is an abutment or finger 46 on one leg 32 of theinverted U-shaped structure 30. At 47 there is a fixed upright channelon which are upper and lower limit switches or valves 48 and 49respectively, 48 being arranged to be engaged by this finger. The uppervalve 48 is adjustable up and down on the upright 47. When the finger 46strikes this switch, the upward movement of the ram is stopped and itsdownward travel initiated.

Lower switch 49 is positioned to be tripped on the down stroke of theram, near the lower limit of its travel, and its function is to effectthe lowering of the stop 40 so that the next unit can be carried intoposition over the ram when the ram is back down to its lower limit oftravel. While it might be arranged that finger 46 also trips valve 49,this operation is preferably effected by valve operator 50 on the leg 32below the finger 46, and hence trip the valve 49 a little sooner so thatthe next unit may actually start to move toward the ram a little sooneron the down stroke of the ram. Valve operator 50 is designed with afinger arranged to ride past switch 49 on the upstroke and trip thevalve only on the down stroke. By adjusting the position of the limitswitch 48 the stroke of the ram may be decreased or increased asrequired for high or low cases or other units.

THE LIFTED UNIT SUPPORTS OR DOGS When a case or other unit has beenlifted by the upward movement of the ram, it must be removed from theplate 31 and supported at an elevated level until a stack is formed.This is accomplished by shelf-like supporting dogs selectively fixed atthe desired elevation on the upright frame 20, one at each side of themachine. The higher the cases or other units, the higher are the dogsset above the conveyors. Also there are guides above these dogs at eachside of the machine for keeping the cases centered one above the otherand stabilizing the stack as it is being formed.

As shown in FIGS. 1, 2, 3 and 11, these dogs each comprise a metal tiltplate 60 welded to the under side of a rock shaft 61 so that each mayswing in a vertical arc. Each plate is unbalanced on the shaft 61 withthe unbalanced overhanging end projecting laterally toward thelongitudinal center line of the machine. The rock-shaft is supported ateach end in a bearing 64, the bearing at one end being carried on asupporting plate 65 and at the other end on a similar plate 66. Theplate 65 for each dog is supported on one of the upright columns 21, oneat one side of the machine and one at the other. Similarly plates 66 arebolted to their respective columns 22. The bolts 67 pass throughselected holes 25 in the columns on which the plates are mounted so thatall four supporting plates are at the same level, and the bolts passthrough elongate slots 68 in the respective plates 65 and 66 so that thetwo plates 65 may be adjusted toward and away from each other and theplates 66 are similarly adjustable. The tilt plates or dogs 60 arerestrained from dropping below a horizontal position by an angularbracket 69 on the plates 65. Each of said plates 60 has notches 70 inthat edge which is toward the center of the machine to clear the guidebars which are hereinafter described.

With this arrangement the dogs 60 at each side of the machine can beadjusted vertically as required by the height of the units and towardand away from each other and symmetrically with respect to thelongitudinal axis of the machine as required by the width of the units.

Above the dogs and their supporting plates there are four other plates71, one on each of the posts or columns 21 and each of the posts orcolumns 22. These plates are bolted to their respective posts forvertical adjustment by selection of the proper holes 25 and haveelongate horizontal slots 72 therein for adjustment toward and away fromeach other. The two support plates 71 at each side of the machine arejoined by a connecting rail 73 parallel with the longitudinal axis ofthe machine. Each connecting rail in turn carries two vertical parallelguide bars 74 with outwardly-flared lower terminal portions 75. Thesebars center and stabilize the stack as it is being formed, ashereinafter more fully appears. In the drawing, for purpose ofillustration, they are illustrated above their normal level, since, atthe normal level the notches 70 are provided in the dogs to clear thelower ends of these rods when the dogs swing up.

When a case is lifted by support 31 and ram 32 it pushes up against theoverhanging edges of the two dogs or hinged plates 60, swinging them ina vertical arc upwardly, but their edges bear against the sides of thecase, since they are overbalanced or biased to return to the horizontalposition. When the case clears the upper edges of the dogs they swingdown to a horizontal position but they are so spaced that they do notproject inwardly toward the longitudinal center of the machine farenough that they can project under the plate 31; in fact the legs 32 areguards against any such possibility. At this time the ram reverses andas it lowers, the dogs, projecting under the edges of the case, willsupport the case against further downward travel.

When a second case follows, it will be pushed up in like manner, liftingwith it the first case, and as the ram lowers, the first case will be ontop of the second one and the second one will be supported on the dogs.This stacking by adding one beneath those above will be repeated until astack of the desired height, stabilized between the guide bars 74, hasbeen reached. The guide bars can be adjusted as needed to meet thedimensions of the cases or other units.

STACK REMOVAL Let it be supposed, for example, that the stacks are toeach be three units high. As indicated in'FIG. 6, the first two unitswill be supported on the dogs as above described and indicated C and CThe third unit, C is carried by the conveyors directly beneath thesetwo, where it will be raised by the ram in the manner described untilit, too, is above the top edges of the dogs 60. By this time, the totalstack of three units will be so high that C will strike and lift theterminal of a rod 81 adjustably fixed to and depending from a lever 82.The lever 82 extends outwardly from a pivoted cam disk 84 fixed forselective vertical adjustment on one of the upright columns 22. As theterminal 80 pushes up on rod 81 the disk 84 will rotate, the directionof rotation being indicated as clockwise by the arrow in FIG. 2. The camelement 85 on the periphery of this disk will operate air valve orswitch 86.

It will be noted, and as best seen in FIG. 10, that each one of the twomounting plates 65 has a horizontallypositioned air cylinder fixedthereto with a pistonoperated piston rod 91 having a free terminalelement 92 thereon. Air pipes 93 and 94 supply pressure air to move thispiston to the right or left, respectively, as viewed in FIG. 10.

At the instant valve 86 is tripped by the raising of lever 82, pressurewill be supplied by such action of the valve 86 through pipe 93 to movethe piston of cylinder 90 toward the right, as here shown, pushing theterminal 92 against the edge of plate 60 below the pivot shaft 61 tomove the plate 60 to a position where it is entirely clear of contactwith the units in a stack and hold it nearly vertical so that it cannotfall back to the loadsupporting position. It should be kept in mind thatthere is such a mechanism on each of the two mounting plates 65, bothcontrolled by the one valve 86. With the dogs 60 thus held in aninoperative position the stack of three cases will be lowered with thelowering of the ram-supported plate 31.

When the valve 86 is tripped, it will also supply pressure air to thetop of cylinder 44 to lower the stop 43 to its inoperative position sothat as the bottom of the stack comes to rest on the conveyor chains 8the stack will be carried by the conveyors toward the delivery ordischarge end of the machine. Since the finished stack is moved out ofthe upright frame by the same conveyors that advance a new case for thestart of the next stack, there is no problem of the likelihood of a newcase being moved into position to start the next stack until thecompleted stack is sufficiently clear of the upright structure 20. Thereis another switch or air valve 100 similar to 42 below the plate 19b andlocated a short distance beyond the stop 43. It is arranged to beengaged by the leading edge of the stack. When this valve is operatedthe stop 43 will be raised, and the two cylinders 90 will be operated towithdraw the terminals 92 of the piston rods 91 from contact with theirrespective dogs 60 so that by their over-balance, they will drop totheir horizontal position. The lever 82 with its rod 81 and terminal 80,being weight-biased, will swing back to its normal position shown inFIG. 2 where a fixed supporting pin 81a prevents it from dropping belowa predetermined level. These operations, having all taken place, themachine will be ready to start the next stack when the next unit, whichmay have already cleared stop 40, reaches stop 43 with its trip valve45.

It should be noted that the dogs 60as seen for example in FIG. 2must beabove the level of the top of unit C sothat the unit'may travel underthem to engage trip valve 45. Hence vertical adjustment of the dogs toclear higher cases or cartons, or whatever is being stacked isimportant. If, however, these plates were at a fixed height above thehighest unit so that any case of a lower size could pass under it, therewould not only be lost motion, slowing the cycle for lower cartons, butwhereas it may be practical to form a stack which is only three caseshigh with boxes or cartons, it may be desirable to stack seven or eightshallow wide boxes. Adjustment of the elements for various heights andwidths therefore increases substantially the utility of the machine anddecreases cost, since a customer can order a machine from stock and notrequire a custom-built machine for his particular size of unit, and ifhe has a run of one size and then another, he can quickly adjust hismachine to the requirements of the different sizes of units.

The air system for effecting the various operations is conventional andcomprises standard equipment which is well known to those skilled insystems of this kind. FIG. 15, for purpose of illustration, showsschematically a simplified circuit for the machine described. Referringto FIG. there are three main four-way sliding valve units 105, 106, and107 to which pressure air, regulated and controlled as usual, issupplied from a source (not shown) through pipe 108, and branches 109,110 and 111 respectively.

The first valve supplies the air to cylinder 41 for rais-' ing andlowering the stop 40. When valve 42 is momentarily depressed, pressureis relieved in pipe 42a causing the valve element of unit 105 to move toa position where pressure air is supplied through pipe 41a to raise thestop while pressure in the top of the cylinder 41 is relieved throughpipe 41b. When valve 49, operated as the ram reaches its lowermostposition is tripped, relieving pressure in this line, valve 105 moves inthe reverse direction to supply pressure air to the top of cylinder 41through pipe 41b and relieve pressure at the lower end of said cylinderthrough pipe 41a.

The second valve 106 directs the flow of air to operate the ram. Whenvalve 45 on stop 43 is tripped, it releases pressure in line 45a,causing valve 106 to move to a position where pressure air is suppliedthrough pipe 340 to the lower end of cylinder 34 to lift the ram, andair from the top of the cylinder will be exhausted through line 34b.When the ram has lifted to trip valve 48, valve 106 will be shifted toreverse this flow and lower the ram.

Valve 107 does two things. It supplies air to cylinder 44 to move stop43 up and down and to the cylinder that control the hold and release ofthe dogs. When stack height limit switch 86 is tripped, valve 107 isoperated to supply pressure air through pipe 93a to pipes 93 to actuatethe dog-holding devices 92 to operative or hold position. It alsosupplies air through pipe 44a to lower the stop 43.

When switch is tripped, valve 107 reverses the pressure air which isdirected through pipe 44b to cylinder 44 to raise stop 43. At the sametime pressure air is supplied through pipe 94a to pipe 94 to the ends ofcylinder 90 to retract the dog-holding terminals to the position wheredogs 60 can drop to their horizontal position.

In some instances the trip valves may be electric switches that wouldelectrically operate the air valves or solenoids to accomplish thefunctions of airoperated mechanisms, as is also well known in the art.horizontally-movable Instead of using hinged dogs as shown in detail inFIG. 11, it may be desirable in some cases to use horizontally-slidingdogs, as shown in FIG. 12 which illustrates one end of one of a pair ofsuch dogs. There is a supporting plate 65 similar to plate 65 in FIG.11. Each supporting plate has a pair of vertically-spaced ears 110 whichslidably support one end of a horizontallydog 111. There is an aircylinder 112 similar to air cylinders 90 with air pipes at each endsimilar to cylinder 90. The piston rod 113 of the piston in cylinder 112is connected at 114 to the dog 111 for reciprocating said doghorizontally.

The function of the sliding dogs 111 is generally the same as thefunction of dogs 60, but the air valving is such that when the trip 45is activated, the cylinders 112 will be operated to withdraw the dogsfrom the path of the upwardly-rising plate 31 with the case which is onit, thereby allowing this case to be moved to a level above the dogs.When air valve 48 is tripped, the dogs on opposite sides of the machinewill slide toward each other by reverse operation of cylinder 112 andits several counterparts, but not sufficiently for the dogs to interferewith the downward travel of the ramsupported plate or platform 31. Inbrief, the sliding dogs operate each time a case is raised, but when theheight valve 86 is tripped, the dogs will not move inwardly topackage-supporting position until the trigger 45 is next operated forthe start ofa new stack. One advantage of this arrangement over thehinged dogs of FIG. 11 is that each case does not need to be lifted ashigh where the dog slides horizontally.

In some instances it may be desirable to remove the stack at a levelabove the level of the case conveyor chains 8, either in the samedirection as that in which the chains are moving, or in the reversedirection or to one side or the other at 90 to the direction in whichsaid conveyors travel. In FIG. 10 this is illustrated with the stackremoval being onto a stack removal conveyor 115 at the left side of themachine as here diagrammed. For this purpose the upwardly-swinginghinged dogs 60 are at right angles to the position shown in FIGS. 1 to3. There is a pusher plate 1 16 operated by a fluid pressurecylinder-piston unit 117 which is normally in a retracted position atthe right of the vertical frame at a level clear of the top of dogs 60when they are in the horizontal position and which is short enough, orotherwise so arranged, that the pusher plate in its retracted positiondoes not interfere with the upward swinging of the dogs 60 or upwardtravel of each case as it is raised by the ram in the manner heretoforedescribed. The cylinders 90 to momentarily hold the plates vertical asthe stack is clearing the frame are not required in this instance, butwhen the stack height switch 86 is tripped, as heretofore described, itwill effect the operation of the pusher plate by operatingcylinder-piston unit 117 to drive the pusher to the left as hereillustrated to discharge the stack onto stack-removal conveyor 115. Inthis instance there may be a flag switch 118 positioned to be operatedby the emerging stack to take the place of flag switch 100 on plate 19b.

If the stack is to be discharged to the right of the upright frame 20instead of the left, the parts above described are simply shifted 180,but if the stack is to be removed in the direction of the travel of theconveyor chains or opposite thereto but at the higher level, the dogsextend in the same direction as shown in FIGS. 1 to 3 but the pusherarrangement, flag switch 118 and conveyor 115 will be disposedlengthwise of the machine but elevated above the conveyor chain 8 therequired'height.

In many places where a stacking machine of this kind is needed, cartonsto be stacked are delivered to the machine with en and side flapsincompletely closed, and if they were moved toward the stacking area inthis condition the flaps, especially the side flaps, would jam againstthe dogs 60 or 111, as the case may be, and possibly cause damage to thecartons, or the machine or the product in the cartons. With hinged dogs60 the first such carton might hinge the dogs upwardly, but after onecarton was then supported on the dogs, the second carton could notenter. To prevent this, the vertical structure 20 may also support acarton flap-closing unit of any preferred or conventional form asindicated in FIG. 13. Here the carton-closing device is indicatedgenerally as 120. It is adjustably secured to the frame 20 on that sideof the frame. which faces the oncoming traffic. It has the conventionalguide member 121 that presses down the small inside flap at the front ofthe carton. There is a cylinder-powered flap-folding element 122 on alever 123 that is swung in an are about pivot 124 by a pressurecylinder-piston unit 125 on a bracket 126. It swings in between the twopartially open side flaps of the carton and depresses the end flap ofthe carton at the trailing end of the carton. Two fixed curved shoes orguides 127, only one of which is seen in the drawings, are positioned todepress the two side flaps, in a manner well understood in the art andhold them down, overlapping the end flaps until the carton moves underthe dogs 60, or 111 in position to be lifted.

Also the flap-closing device 120 will have associated therewith glueapplicators (not shown) for applying glue to the top of the end flaps sothat the side flaps will be glued shut as they are folded down, or gluemay be so applied before the cartons are delivered to the stacker. Also,it may often be desired to glue one unit in a stack on top of another bya severable glue. In this case glue is not applied to the outside of theside flaps of the first carton in a stack, but would be applied to thetops of the succeeding cartons of the same stack so that as eachsucceeding carton was pressed against the bottom of the carton above,the two cartons would be glued together. This involves only conventionalglue applicators.

For applying pressure to the'flaps after they have been glued, and tocartons in the stack if the cartons in the stack are glued to oneanother, there is a floating weight in the frame 20 suspended from oneor more guide rods 131 slidable through the top of the frame, with alimiting nut or other abutment 132 at its upper end to limit itsdownward movement. As each carton is lifted the top carton pressesagainst the weight 130 and lifts it and then as the weight follows thecompleted or incompleted stack down it continues to exert pressure. Onlya brief time is required for the glue to set.

In place of the floating weight just described, there may be a pressureroller 135 on the frame 20 at the outgoing side beneath which the stack,as it leaves the frame 20 must pass and be momentarily pressed betweenthe roller at the top and the conveyor and table structure at thebottom. The flap-folding arrangement of FIG. 13 would of course be usedalong with some kind of gluing applicators, as previously described inFIG. 13. With the arrangement shown in either FIGS. 13 or 14, theconveyor chains may require upstanding flights on the conveyor chains topositively push the cartons under the flap-closing device, in which casethe trigger 45 stops the conveyor belts and 49 starts them. In this casestop 40 may not be necessary.

While case or like stackers of this general type have heretofore beenproposed, the present invention embodies certain novel concepts in arelatively inexpensive machine. One is the ready adjustability of themachine to stacking cases or cartons of different widths and differentheights. The location of the switches 48 and 49 to be operated by theinverted U-shape frame 30 with switch 48 being adjustable up or down toregulate the travel of the ram and the frame to suit the thickness ofthe cases being stacked assures that this switch or valve cannot beaccidentally tripped. The machine is unique in that the lowermost cartonin the stack is lifted by the ram the same distance as each of the othercartons in the stack. This avoids the necessity of providing for ashorter stroke or different cycle of the ram when the stack has reachedits full height, and whether the hinged dogs 60 or the sliding dogs 111are used, these dogs are held clear of the sides of the stack when thestack is moved out of the frame 20 to the discharge end of the machine.Moreover this same facility enables the stack to be removed at a levelabove the level of conveyor chains 8 so that one machine, with littleexpense, such as the addition of the pusher arrangement of FIG. 10 canbe adapted to various plant environments or requirements, providinggreat versatility without each machine being custom-built for the shopin which it is to be used. By providing the carton flap-closing unitimmediately in advance of the stacking mechanism a further importantutility is provided. The floating weight arrangement of FIG. 13 or thepressure roller of FIG. 14 is of considerable importance where cartonflaps are to be glued, or the cartons in a stack glued together. Thepneumatic circuitry and valves are standard equipment, as are thecylinderpiston units so that the machine can be assembled from standardstructural sections and off-the-shelf parts with very little machinework being required. By having parallel conveyor chains with thesupporting plates 18, 19a and 19b, together with adjustable guide bars12, two smaller units may be stacked side-by-side as a single unit, andat other times two smaller units may be placed in abutting end-to-endposition and stacked as a single unit. Also, while in the specificexamples here used the stack comprises more than two units, in manyinstances a stack will be but two units high.

I claim:

1. Apparatus for arranging similar units into vertical stacks ofpredetermined height comprising:

a. a supporting frame with parallel sides and with ahorizontally-extending conveyor means thereon comprising two parallelendless conveyors, one near each side of the frame with a space betweenthem, the frame and conveyor having a receiving end onto which units tobe stacked are placed in succession and a delivery end opposite thereceiving end,

b. elevator means on the frame intermediate the two ends thereof andpositioned in the space between the two endless conveyors, said elevatormeans having a platform which has a lower position over which units tobe stacked are carried in succession by the conveyor means arranged toelevate each unit in turn to a selected uniform level above the conveyormeans, with each succeeding unit after the first in a stack being raisedunderneath the one ahead until the stack comprises a predeterminednumber of units and is of a predetermined height, the elevatorcomprising also a fluid pressureoperated ram on which the platform isfixed and by which it is moved vertically,

c. said frame having upwardly-extending frame members at each sidethereof between which the elevator lifts the units to form a stack, theside frame members each having a unit-supporting dog thereon with thedog on one side being directly opposite the one on the other side, saiddogs being movable in a vertical arc between a position where they areclear of the upward travel of the elevator platform but project under aunit raised above the level thereof by said platform to a positionentirely clear of any contact with the units, there beinghorizontally-acting cylinder and piston units arranged to move and holdsaid dogs in position where they are entirely clear of any contact withthe units and effecting their return to a position where they may extendunder a unit that has been elevated by the platform,

d. fluid pressure-actuated means controlled by the height of the stackof units above said dogs for selectively holding said dogs out ofunit-contacting position whereby the completed stack may then be loweredinto said conveyor means to be carried thereby to the delivery end ofthe conveyor.

2. Apparatus as defined in claim 1 in which said means for holding thedogs out of unit-contacting position is rendered inoperative and apusher means is arranged to slide each completed stack while it issupported on said dogs at an elevation above the level of the conveyormeans.

3. Apparatus as defined in claim 2 where the dogs are crosswise of theconveyor means and said pusher is arranged to push the completed stackto one side of the supporting frame in a direction transverse to thedirec-v tion of travel of the conveyor means.

4. Apparatus as defined in claim 1 in which said dogs each comprise apivoted plate biased to swing to a horizontal unit-supporting positionbut is free to swing upwardly by contact with a unit being lifted bysaid elevating means, and wherein means is provided for restraining eachof said dogs so biased from swinging down to the horizontalunit-supporting position, the apparatus having means actuated by contactwith the stack only when the stack has reached a predetermined heightfor operating said restraining means to keep the dogs from swinging downto load-supporting position whereby the completed stack may then belowered past said dogs onto the conveyor means to be carried thereby tothe delivery end of the conveyor, and other means effective upon travelof the completed stack toward said delivery end for releasing saiddog-restraining means whereby the dogs are restored to a free-swingingcondition for the forming of the next stack.

5. Apparatus as defined in claim 1 in which the dogs and thehorizontally-disposed cylinder and piston units for the respective dogsare mounted for adjustment horizontally toward and away from each otherand vertically with respect to the conveyor to thereby accommodate unitsof different widths and different heights, the frame havingtransversely-adjustable longitudinally-extending guide rails at eachside thereof, the adjustment of which enables units of a preselectedwidth to be kept centered over the elevator platform.

6. The apparatus defined in claim 1 wherein said elevator platform has adepending leg element thereon which has a laterally-projecting flagswitch-engaging means thereon, and a pair of vertically-spaced flagswitches positioned on the frame to be operated by the movement of theprojection on said leg past said switches, the upper flag switch beingarranged to reverse the travel of the ram when it has reached thepredetermined level above the conveyor and the lower one of which isarranged to operate a control means for passing the units one at a timeto the elevator, said upper flag switch comprising the only ram-operatedmeans for reversing the travel of the ram.

7. Apparatus as defined in claim 6 wherein the upper flag switch isvertically adjustable in the frame to adjust the extent of up and downtravel of the ram.

8. Apparatus as defined in claim 1 wherein said conveying meanscomprises a pair of parallel endless chain conveyors driven together asa unit but spaced from each other and from the sides of the frame andthere is a vertical frame structure extending upwardly from the sides ofthe supporting frame at each side of said unit-elevating means, theopposed dogs being supported on said vertical frame structure at eachside of the frame, and means on said vertical frame structure projectingtoward the receiving end of the conveyor means for folding down all theflaps of a unit which is a carton to a level below the level of the dogsso that the unit may be conveyed under said dogs onto the elevatingmeans.

9. Apparatus as defined in claim 8 in which the dogs are verticallyadjustable on the vertical frame structure and the flap closure is alsovertically adjustable.

10. Apparatus as defined in claim 8 wherein the vertical frame structurehas a weight slidably suspended from the top thereof in position to beengaged and lifted by the stack as it is being progressively formed andthereby exert a pressure on the closed carton flaps to hold them downwhile glue may be setting or if one carton is being glued atop another.

11. Apparatus as defined in claim 1 wherein said vertically-extendingside frames also support means extending toward the receiving endarranged to fold down the flaps of a unit where such unit is a cartonwith flaps incompletely closed to an extent where the flaps will be at alevel below the dogs when the unit moves into position over the elevatorplatform.

12. Apparatus for arranging similar units into vertical stacks ofpredetermined height comprising:

a. a supporting frame with parallel sides and with ahorizontally-extending conveyor means thereon comprising two parallelendless conveyors, one near each side of the frame with a space betweenthem, the frame and conveyor having a receiving end onto which units tobe stacked are placed in succession and a delivery end opposite thereceiving end,

b. an elevator on the frame intermediate the two ends thereof andpositioned in the space between the two endless conveyors, said elevatorhaving a platform which has a lower position over which units to bestacked are carried in succession by the conveyor means and arranged toelevate each unit in turn to a selected uniform height above theconveyor with each succeeding unit in the stack after the first onebeing raised underneath the preceding one until the stack comprises apredetermined number of units and is of a predetermined height, theelevator comprising also a fluid pressureoperated ram on which theplatform is fixed and by which it is moved vertically,

c. a vertically-movable stop means normally positioned to stop each unitas it moves in position over the elevator to be lifted, said stop meansbeing movable from said normal position to a position out of the planeof travel of a unit supported on the conveyor means, said stop meanshaving a first trip means thereon arranged to be operated when the stopmeans is in normal position by a unit which is carried by the conveyormeans contacts it, said trip means being arranged to energize the ram toeffect the raising of the elevator,

d. elevator control means arranged to always reverse the upward travelof the elevator at the same preselected level comprising a second tripmeans on the frame below the elevator, and means on the elevator belowthe platform for operating said second trip means on the upward travelof the elevator to thereby effect the lowering of the elevator back tosaid lower position, said second trip means comprising the only meansresponsive to the travel of the elevator including any stack which itlifts for reversing the travel of the elevator,

e. said frame having upwardly-extending frame members at each sidethereof between which the elevator lifts the units to form a stack, theupwardlyextending side frame members each having a unitsupporting dogthereon pivoted to swing in a vertical arc with the opposing dogspositioned to clear the path of travel of the elevator platform but tobe engaged and swung upwardly from a horizontal position toward avertical position by contact with a unit being lifted by the elevator,said dogs each being biased to swing back to a horizontal position wherethey each project under a unit after the elevator platform has moved toa level above the tops of the supporting dogs, whereby the dogs supportthe bottom of each unit in turn as it is lifted by the elevator and theelevator then descends,

f. a second trip means in position to be engaged by the top of the stackas the last unit is lifted into place and arranged (l) to move saidverticallymovable stop and its said first trip out of unitobstructingposition, and (2) move and hold said dogs in a nearly vertical positionclear of contact with the units of the stack and prevent their moving toa horizontal load-supporting position whereby the stack of units maythen be lowered by the elevator platform onto the conveyor means to becarried without obstruction from said stop toward said delivery end, and

i g. means in the path of travel of the stack between thevertically-movable stop and the delivery end of the conveyor forrestoring said stop with its first trip means into unit-obstructingposition and simultaneously release said dogs whereby they may return totheir horizontal position.

13. Apparatus as defined in claim 12 for arranging similar units into avertical stack of predetermined height wherein each saidvertically-swinging dog is moved to the nearly vertical position out ofcontact with the units and its return to a horizontal position iseffected through a horizontally-disposed fluid pressure cylinder andpiston unit fixed to the upwardlyextending frame members adjacent thedog which it moves with a piston rod operatively engaging the dog.

14. Apparatus as defined in claim 12 for arranging similar units into avertical stack in which said vertically-swinging dogs and theirrespective cylinder and piston units are mounted on mounting memberswhich are adjustable vertically and horizontally on their respectivelyvertically-extending frame members whereby the dogs may be adjusted toclear the tops of the units as they are carried by the conveyor toposition over the elevator.

15. Apparatus as defined in claim 12 wherein said trip means on theframe below the elevator platform is vertically adjustable to adjust thevertical travel of the elevator relative to the height at which saiddogs are positioned.

16. Apparatus as defined in claim 12 for arranging similar units into avertical stack of predetermined height wherein there is a secondvertically-movable stop means between the receiving end of the conveyorand the elevator movable betweena raised position where it obstructs thetravel of a unit into position over the elevator to a lowered positionclear of the travel of th units, the fluid pressure cylinder for raisingand lowering the stop, a fluid pressure valve between the stop and theelevator arranged to be operated by the travel of a unit between thestop and the elevator to actuate said fluid pressure cylinder to raisethe stop, and a second trip means on the frame arranged to be engaged bysaid means below the elevator to actuate said fluid pressure cylinder tolower the stop means as the elevator reaches its lowermost position.

17. Apparatus for arranging units into vertical stacks of predeterminedheight comprising:

a. a supporting frame with parallel sides and with ahorizontally-extending conveyor means thereon, the conveyor meanscomprising two spaced parallel endless conveyors with means forcontinuously driving them in unison, the conveyor and frame having areceiving end onto which units to be stacked are placed and a deliveryend opposite the receiving end,

b. an elevator located intermediate the said two ends and positionedbetween the two endless conveyors,

c. a first vertically-movable stop between the receiving end of theconveyor and the elevator for selectively controlling the movement ofunits by the conveyor means into position over the elevator,

d. a second vertically-movable stop means adjacent the elevator forstopping each unit as it is moved by the conveyor means over theelevator,

the frame having upwardly-extending guiding frame structures, one ateach side thereof in transverse alignment with the elevator, each suchupwardly-extending frame structure having a supporting plate thereonmovable between a verticallyextending position where it is clear of anycontact with the load at all and a horizontally-extending position whereeach projects under a unit which has been raised by the elevator to thenbe supported when the elevator descends, the plates at the two sidesacting together to support the units of an incomplete stack as each unitis added,

. the elevator comprising a platform and a fluidpressure cylinder andpiston below the platform for raising and lowering it, the first andsecond stops each having its own fluid pressure-operated cylinder andpiston for raising and lowering it, each of said plates having its ownfluid pressure-operated cylinder and piston unit for operating it, and

g. a first fluid pressure trip valve on the frame below the elevator andfluid pressure circuit controlled thereby arranged to be tripped by theelevator as it reaches its lower limit of travel for lowering saidfirststop, a second fluid pressure trip valve between said first stop and theelevator and fluid pressure circuit controlled by it arranged to raisesaid first stop by supplying pressure to the cylinder and piston unitfor that stop to effect the raising thereof when a unit moves past ittoward the elevator; a third trip valve on said second stop arranged tobe contacted and operated by a unit moving on said conveyor intoposition over the elevator and an associated fluid pressure circuitcontrolled thereby to effect operation of the elevator fluid pressurecylinder and piston to effect the raising of said elevator, a fourthtrip valve on the frame under the elevator and associated fluid pressurecircuits arranged to be operated by the upwardly-moving elevator toreverse the fluid pressure to the elevator operating cylinder and causethe elevator to lower, a fifth trip valve and associated fluid pressurecircuit arranged to be operated by a stack of predetermined height forsimultaneously supplying fluid pressure to the cylinders which operatethe supporting plates to move them out of unit contacting position andat the same time supply fluid pressure to the cylinder and piston unitfor lowering said second stop, and finally a sixth trip valve on theframe spaced toward the delivery end of the conveyor beyond the secondstop and associated fluid pressure circuits for simultaneously operatingthe cylinder and piston units for the supporting plates in the reversedirection to restore them to unit-supporting position and at the sametime effect the raising of said second stop.

1. Apparatus for arranging similar units into vertical stacks ofpredetermined height comprising: a. a supporting frame with parallelsides and with a horizontally-extending conveyor means thereoncomprising two parallel endless conveyors, one near each side of theframe with a space between them, the frame and conveyor having areceiving end onto which units to be stacked are placed in successionand a delivery end opposite the receiving end, b. elevator means on theframe intermediate the two ends thereof and positioned in the spacebetween the two endless conveyors, said elevator means having a platformwhich has a lower position over which units to be stacked are carried insuccession by the conveyor means arranged to elevate each unit in turnto a selected uniform level above the conveyor means, with eachsucceeding unit after the first in a stack being raised underneath theone ahead until the stack comprises a predetermined number of units andis of a predetermined height, the elevator comprising also a fluidpressure-operated ram on which the platform is fixed and by which it ismoved vertically, c. said frame having upwardly-extending frame membersat each side thereof between which the elevator lifts the units to forma stack, the side frame members each having a unit-supporting dogthereon with the dog on one side being directly opposite the one on theother side, said dogs being movable in a vertical arc between a positionwhere they are clear of the upward travel of the elevator platform butproject under a unit raised above the level thereof by said platform toa position entirely clear of any contact with the units, there beinghorizontally-acting cylinder and piston units arranged to move and holdsaid dogs in position where they are entirely clear of any contact withthe units and effecting their return to a position where they may extendunder a unit that has been elevated by the platform, d. fluidpressure-actuated means controlled by the height of the stack of unitsabove said dogs for selectively holding said dogs out of unit-contactingposition whereby the completed stack may then be lowered into saidconveyor means to be carried thereby to the delivery end of theconveyor.
 2. Apparatus as defined in claim 1 in which said means forholding the dogs out of unit-contacting position is rendered inoperativeand a pusher means iS arranged to slide each completed stack while it issupported on said dogs at an elevation above the level of the conveyormeans.
 3. Apparatus as defined in claim 2 where the dogs are crosswiseof the conveyor means and said pusher is arranged to push the completedstack to one side of the supporting frame in a direction transverse tothe direction of travel of the conveyor means.
 4. Apparatus as definedin claim 1 in which said dogs each comprise a pivoted plate biased toswing to a horizontal unit-supporting position but is free to swingupwardly by contact with a unit being lifted by said elevating means,and wherein means is provided for restraining each of said dogs sobiased from swinging down to the horizontal unit-supporting position,the apparatus having means actuated by contact with the stack only whenthe stack has reached a predetermined height for operating saidrestraining means to keep the dogs from swinging down to load-supportingposition whereby the completed stack may then be lowered past said dogsonto the conveyor means to be carried thereby to the delivery end of theconveyor, and other means effective upon travel of the completed stacktoward said delivery end for releasing said dog-restraining meanswhereby the dogs are restored to a free-swinging condition for theforming of the next stack.
 5. Apparatus as defined in claim 1 in whichthe dogs and the horizontally-disposed cylinder and piston units for therespective dogs are mounted for adjustment horizontally toward and awayfrom each other and vertically with respect to the conveyor to therebyaccommodate units of different widths and different heights, the framehaving transversely-adjustable longitudinally-extending guide rails ateach side thereof, the adjustment of which enables units of apreselected width to be kept centered over the elevator platform.
 6. Theapparatus defined in claim 1 wherein said elevator platform has adepending leg element thereon which has a laterally-projecting flagswitch-engaging means thereon, and a pair of vertically-spaced flagswitches positioned on the frame to be operated by the movement of theprojection on said leg past said switches, the upper flag switch beingarranged to reverse the travel of the ram when it has reached thepredetermined level above the conveyor and the lower one of which isarranged to operate a control means for passing the units one at a timeto the elevator, said upper flag switch comprising the only ram-operatedmeans for reversing the travel of the ram.
 7. Apparatus as defined inclaim 6 wherein the upper flag switch is vertically adjustable in theframe to adjust the extent of up and down travel of the ram. 8.Apparatus as defined in claim 1 wherein said conveying means comprises apair of parallel endless chain conveyors driven together as a unit butspaced from each other and from the sides of the frame and there is avertical frame structure extending upwardly from the sides of thesupporting frame at each side of said unit-elevating means, the opposeddogs being supported on said vertical frame structure at each side ofthe frame, and means on said vertical frame structure projecting towardthe receiving end of the conveyor means for folding down all the flapsof a unit which is a carton to a level below the level of the dogs sothat the unit may be conveyed under said dogs onto the elevating means.9. Apparatus as defined in claim 8 in which the dogs are verticallyadjustable on the vertical frame structure and the flap closure is alsovertically adjustable.
 10. Apparatus as defined in claim 8 wherein thevertical frame structure has a weight slidably suspended from the topthereof in position to be engaged and lifted by the stack as it is beingprogressively formed and thereby exert a pressure on the closed cartonflaps to hold them down while glue may be setting or if one carton isbeing glued atop another.
 11. Apparatus as defined in claim 1 whereinsaid vertically-extending side frames aLso support means extendingtoward the receiving end arranged to fold down the flaps of a unit wheresuch unit is a carton with flaps incompletely closed to an extent wherethe flaps will be at a level below the dogs when the unit moves intoposition over the elevator platform.
 12. Apparatus for arranging similarunits into vertical stacks of predetermined height comprising: a. asupporting frame with parallel sides and with a horizontally-extendingconveyor means thereon comprising two parallel endless conveyors, onenear each side of the frame with a space between them, the frame andconveyor having a receiving end onto which units to be stacked areplaced in succession and a delivery end opposite the receiving end, b.an elevator on the frame intermediate the two ends thereof andpositioned in the space between the two endless conveyors, said elevatorhaving a platform which has a lower position over which units to bestacked are carried in succession by the conveyor means and arranged toelevate each unit in turn to a selected uniform height above theconveyor with each succeeding unit in the stack after the first onebeing raised underneath the preceding one until the stack comprises apredetermined number of units and is of a predetermined height, theelevator comprising also a fluid pressure-operated ram on which theplatform is fixed and by which it is moved vertically, c. avertically-movable stop means normally positioned to stop each unit asit moves in position over the elevator to be lifted, said stop meansbeing movable from said normal position to a position out of the planeof travel of a unit supported on the conveyor means, said stop meanshaving a first trip means thereon arranged to be operated when the stopmeans is in normal position by a unit which is carried by the conveyormeans contacts it, said trip means being arranged to energize the ram toeffect the raising of the elevator, d. elevator control means arrangedto always reverse the upward travel of the elevator at the samepreselected level comprising a second trip means on the frame below theelevator, and means on the elevator below the platform for operatingsaid second trip means on the upward travel of the elevator to therebyeffect the lowering of the elevator back to said lower position, saidsecond trip means comprising the only means responsive to the travel ofthe elevator including any stack which it lifts for reversing the travelof the elevator, e. said frame having upwardly-extending frame membersat each side thereof between which the elevator lifts the units to forma stack, the upwardly-extending side frame members each having aunit-supporting dog thereon pivoted to swing in a vertical arc with theopposing dogs positioned to clear the path of travel of the elevatorplatform but to be engaged and swung upwardly from a horizontal positiontoward a vertical position by contact with a unit being lifted by theelevator, said dogs each being biased to swing back to a horizontalposition where they each project under a unit after the elevatorplatform has moved to a level above the tops of the supporting dogs,whereby the dogs support the bottom of each unit in turn as it is liftedby the elevator and the elevator then descends, f. a second trip meansin position to be engaged by the top of the stack as the last unit islifted into place and arranged (1) to move said vertically-movable stopand its said first trip out of unit-obstructing position, and (2) moveand hold said dogs in a nearly vertical position clear of contact withthe units of the stack and prevent their moving to a horizontalload-supporting position whereby the stack of units may then be loweredby the elevator platform onto the conveyor means to be carried withoutobstruction from said stop toward said delivery end, and g. means in thepath of travel of the stack between the vertically-movable stop and thedelivery end of the conveyor for restoring said stop with its first Tripmeans into unit-obstructing position and simultaneously release saiddogs whereby they may return to their horizontal position.
 13. Apparatusas defined in claim 12 for arranging similar units into a vertical stackof predetermined height wherein each said vertically-swinging dog ismoved to the nearly vertical position out of contact with the units andits return to a horizontal position is effected through ahorizontally-disposed fluid pressure cylinder and piston unit fixed tothe upwardly-extending frame members adjacent the dog which it moveswith a piston rod operatively engaging the dog.
 14. Apparatus as definedin claim 12 for arranging similar units into a vertical stack in whichsaid vertically-swinging dogs and their respective cylinder and pistonunits are mounted on mounting members which are adjustable verticallyand horizontally on their respectively vertically-extending framemembers whereby the dogs may be adjusted to clear the tops of the unitsas they are carried by the conveyor to position over the elevator. 15.Apparatus as defined in claim 12 wherein said trip means on the framebelow the elevator platform is vertically adjustable to adjust thevertical travel of the elevator relative to the height at which saiddogs are positioned.
 16. Apparatus as defined in claim 12 for arrangingsimilar units into a vertical stack of predetermined height whereinthere is a second vertically-movable stop means between the receivingend of the conveyor and the elevator movable between a raised positionwhere it obstructs the travel of a unit into position over the elevatorto a lowered position clear of the travel of th units, the fluidpressure cylinder for raising and lowering the stop, a fluid pressurevalve between the stop and the elevator arranged to be operated by thetravel of a unit between the stop and the elevator to actuate said fluidpressure cylinder to raise the stop, and a second trip means on theframe arranged to be engaged by said means below the elevator to actuatesaid fluid pressure cylinder to lower the stop means as the elevatorreaches its lowermost position.
 17. Apparatus for arranging units intovertical stacks of predetermined height comprising: a. a supportingframe with parallel sides and with a horizontally-extending conveyormeans thereon, the conveyor means comprising two spaced parallel endlessconveyors with means for continuously driving them in unison, theconveyor and frame having a receiving end onto which units to be stackedare placed and a delivery end opposite the receiving end, b. an elevatorlocated intermediate the said two ends and positioned between the twoendless conveyors, c. a first vertically-movable stop between thereceiving end of the conveyor and the elevator for selectivelycontrolling the movement of units by the conveyor means into positionover the elevator, d. a second vertically-movable stop means adjacentthe elevator for stopping each unit as it is moved by the conveyor meansover the elevator, e. the frame having upwardly-extending guiding framestructures, one at each side thereof in transverse alignment with theelevator, each such upwardly-extending frame structure having asupporting plate thereon movable between a vertically-extending positionwhere it is clear of any contact with the load at all and ahorizontally-extending position where each projects under a unit whichhas been raised by the elevator to then be supported when the elevatordescends, the plates at the two sides acting together to support theunits of an incomplete stack as each unit is added, f. the elevatorcomprising a platform and a fluid-pressure cylinder and piston below theplatform for raising and lowering it, the first and second stops eachhaving its own fluid pressure-operated cylinder and piston for raisingand lowering it, each of said plates having its own fluidpressure-operated cylinder and piston unit for operating it, and g. afirst fluid pressure trip valve on the fRame below the elevator andfluid pressure circuit controlled thereby arranged to be tripped by theelevator as it reaches its lower limit of travel for lowering said firststop, a second fluid pressure trip valve between said first stop and theelevator and fluid pressure circuit controlled by it arranged to raisesaid first stop by supplying pressure to the cylinder and piston unitfor that stop to effect the raising thereof when a unit moves past ittoward the elevator; a third trip valve on said second stop arranged tobe contacted and operated by a unit moving on said conveyor intoposition over the elevator and an associated fluid pressure circuitcontrolled thereby to effect operation of the elevator fluid pressurecylinder and piston to effect the raising of said elevator, a fourthtrip valve on the frame under the elevator and associated fluid pressurecircuits arranged to be operated by the upwardly-moving elevator toreverse the fluid pressure to the elevator operating cylinder and causethe elevator to lower, a fifth trip valve and associated fluid pressurecircuit arranged to be operated by a stack of predetermined height forsimultaneously supplying fluid pressure to the cylinders which operatethe supporting plates to move them out of unit contacting position andat the same time supply fluid pressure to the cylinder and piston unitfor lowering said second stop, and finally a sixth trip valve on theframe spaced toward the delivery end of the conveyor beyond the secondstop and associated fluid pressure circuits for simultaneously operatingthe cylinder and piston units for the supporting plates in the reversedirection to restore them to unit-supporting position and at the sametime effect the raising of said second stop.